Interlaminar stabilization system

ABSTRACT

A spinal stabilization system includes vertebral engagement members and an intermediate structure. The vertebral engagement members are configured to be disposed between a first vertebra and a second vertebra. The vertebral engagement members generally include seating surfaces for accommodating at least a portion of a laminar region of adjacent vertebra and are adjustable between an operable and inoperable configuration. The intermediate structure extends between the vertebral engagement members. The structural cooperation of the vertebral engagement members and the intermediate structure is such that the engagement members distract the adjacent vertebrae.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Provisional Application Ser. No.60/973,659 filed on Sep. 19, 2007, the disclosure of which is herebyincorporated in its entirety by reference.

FIELD OF THE INVENTION

The present invention relates generally to a spinal stabilization systemand, more particularly, a spinal stabilization system for distractingand limiting reduction of the intervertebral spacing between adjacentvertebrae.

BACKGROUND OF THE INVENTION

This invention pertains generally to medical implantable devices andparticularly to spinal implants. Various devices for internal fixationof bone segments in the human or animal body are known in the art. Themost common type of spinal implant system are hook and rod systems andpedicle screw systems which provides a means of gripping a spinalsegment. However, both hook and rod and pedicle screw systems havelimitations and are not appropriate for all types of spinal disorders.

Conventional hook and rod systems comprise a series of hooks and anelongate rod. Typically, the hooks are positioned against lamina whichare not adjacent one another to decompress or compress a section of thespine. Further, the hooks are positioned before being connected to theconnecting rod, requiring the surgeon to place each individual hookbefore attempting to mount the connecting rod onto the hooks.

A conventional pedicle screw system comprises a pedicle screw and a rodreceiving device. The pedicle screw includes an externally threaded stemand a head portion. The rod-receiving device couples to the head portionof the pedicle screw and receives a rod (commonly referred to as adistraction rod). Two such systems are inserted into respectivevertebrae and adjusted to distract and/or stabilize a spinal column. Thepedicle screw does not, by itself, fixate the spinal segment, butinstead operates as an anchor point to receive the rod-receiving device,which in turn receives the rod. One goal of such a system is tosubstantially reduce and/or prevent relative motion between the spinalsegments that are being fused.

The implantation of pedicle screw systems are intricate, time consuming,and invasive into the spine of the patient. Typically, a series ofpedicle screws must be carefully placed precisely in the narrow pedicleregion of the spine. These pedicle screws are then fitted with rodreceiving devices which are then in turn fitted with distraction rods.The system of screws and rods creates an intricate system for supportingthe spine that takes considerable effort.

The placement of the screws and rods is time consuming because thecomponents must be positioned through trial and error with repeatedadjustment of position of the components until final proper positioningof all the components of the entire system is achieved simultaneously.Finally, the implantation of pedicle screw systems is highly invasivebecause screws must be deeply driven into the pedicle region of thespine within close proximity of the nerves of the spinal cord or spinalnerves branching off of the spinal cord. A more rapid and less invasiveimplantation system was sought to structurally support the spineespecially in spinal stenosis patients where the settling of the spinecauses impingement on the nerves yet the intervertebral discs remainlargely intact.

SUMMARY OF THE INVENTION

In accordance with one form, a spinal implant assembly for engagingadjacent vertebrae includes a pair of vertebral gripping devices and anelongate guide rod which extends along a rod axis between the vertebralgripping devices. The vertebral gripping devices include a body portionconfigured to be secured to the guide rod for translation therealong andhooks that are offset from each other relative to the rod axis, with thetranslatable body portions allowing the offset hooks to be engaged withoffset portions of the adjacent vertebrae for distraction thereof.

One advantage of this form is that it allows the spinal implant assemblyto have a minimal insertion profile. This is beneficial because thesmaller the insertion profile, the less the adjacent vertebrae must bedistracted, if at all, for the spinal implant assembly to be insertedtherebetween.

According to another form, the offset of the hooks is sized to allow thebody portions to be translated toward each other to a compactorientation to minimize space therebetween.

According to another form, the offset hooks extend different distancesalong the rod axis.

According to another form, the hook portions include a contoured surfaceconfigured for engaging a predetermined portion of the vertebrae.

According to another form, the contoured surface includes inner surfaceportions that are inclined relative to each other.

According to another form, the body portion includes an annularthroughbore configured to receive the elongate guide rod.

According to another form, the throughbore is oversized relative to therod to allow the rod to be shifted laterally within the throughbore.

In accordance with a second form, a spinal implant assembly includes afirst body portion, a second body portion, and a rod portion. The firstbody portion includes a first lateral surfaces, and first front surfaceand back surfaces extending laterally between the lateral surfaces. Thesecond body portion including second lateral surfaces, and second frontand back surfaces extending laterally between the lateral surfaces. Therod portion including a longitudinal rod axis with the bodies configuredto be guided for translation along the rod portion from a compactorientation with the back surfaces of the bodies being closely adjacentor engaged with each other and an operable orientation with at least oneof the bodies being shifted along the rod away from the other body to bedistal therefrom. Further, the first body includes a first seat portionincluding a recessed groove therein that extends across a portion of oneof the first lateral surfaces, the first front surface, and across aportion of the other first lateral surface and configured to extendabout an inferior portion of the upper lamina of the adjacent lamina.Additionally, the second body portion includes a second seat portionincluding a second recessed groove therein that extends across a portionof the rear surface, one of the lateral surfaces, the second frontsurface, and across a portion of the other lateral surface andconfigured to extend about a superior portion the upper lamina of theadjacent lamina. The seat portions of the first and second body portionshaving contoured surface portions that allow the seat portions to selfadjust to the contour of the vertebrae when engaged therewith in theoperable orientation thereof.

According to another form, the first seat includes surface portions thatare inclined relative to the rod axis.

According to another form, the second seat includes surface portionsthat are inclined relative to the rod axis.

According to another form, the second body portion is translatable alongthe rod portion.

According to another form, the body portions extend different lengthsgenerally normal to the rod axis.

According to another form, the second seat extends above a lower rodsurface of the rod portion.

According to another form, the rod portion is configured to accept abumper between the first and second body portions.

According to another form, the bumper is resilient.

According to another form, the inoperable orientation is defined by thefirst rear surface of the first body portion being in contact with thesecond rear surface of the second body portion.

In accordance with a third form, a spinal implant assembly includes afirst hook portion, a second hook portion, and a guide mechanismconnecting the first and second hook portions. The guide mechanismincludes a one-way locking mechanism to permit shifting of at least oneof the first and second hook portions from a compact orientation to anoperable orientation and block shifting from the operable orientation tothe compact orientation.

According to another form, the one-way locking mechanism is a ratchetingmechanism.

According to another form, the one-way locking mechanism includescooperating teeth portions each having a camming surface and a stopsurface.

According to another form, the guide mechanism is a pivotal guidemechanism.

According to another form, the pivotal guide mechanism includes a pivotpin that pivotably connects the hooks portions together.

According to another form, the guide mechanism is a linear guidemechanism.

In accordance with a fourth form, a spinal implant assembly includes agenerally U-shaped body, a pair of vertebral engaging arms and a pivotmechanism. The U-shaped body includes a base portion, side arm portionsextending from the base portion, and a stop portion extending betweenthe side arm portions. The pair of vertebral engaging arms areconfigured to be received between the parallel side arm portions andhave inoperable and operable configurations. The a pivot mechanism isconfigured for pivotably connecting the vertebral engaging arms and thebody portion, with the vertebral engaging arms engaged with the stopportion in the operable configuration thereof and pivoted away from thestop portion toward each other in the inoperable configuration.

According to another form, the vertebral engaging arms includeengagement ends and intermediate portions, the intermediate portionsconfigured to have a width less than a width of the engagement ends tominimize space between the vertebral engagement arms in the inoperableconfiguration.

According to another form, one of the vertebral engaging arms includes anarrow proximal end and the other vertebral engaging arm includes aslotted proximal end configured to receive the narrow proximal endtherein.

According to another form, the body portion includes a throughbore andlocking mechanism for engaging the vertebral engaging arms and blockingmovement thereof while in the operable configuration.

According to another form, the throughbore is threaded and the lockingmechanism is a threaded set screw.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a spinal implant assembly according to afirst form of the present invention;

FIG. 2 is an exploded perspective view of the spinal implant assembly ofFIG. 1;

FIG. 3 is a side view of the spinal implant assembly of FIG. 1 showingthe vertebral gripping devices along the rod;

FIG. 4 is a side view of the spinal implant assembly of FIG. 1 in thecompact orientation;

FIG. 5 is a top plan view of the spinal implant assembly of FIG. in thecompact orientation;

FIG. 6 is an end view of the spinal implant assembly of FIG. 1 showingthe offset hooks;

FIG. 7A is a perspective view of the spinal implant assembly of FIG. 1showing two assemblies inserted between adjacent lamina;

FIG. 7B is a top plan view of a vertebral body;

FIG. 8 is a is a perspective view of the spinal implant assembly of FIG.1 showing two assemblies connected by a transverse member;

FIG. 9 is a perspective view of a spinal implant assembly according to asecond form of the present invention;

FIG. 10 is an exploded perspective view of the spinal implant assemblyof FIG. 9;

FIG. 11 is a side view of the spinal implant assembly of FIG. 9 showingthe assembly in the compact orientation;

FIG. 12 is a side view of the spinal implant assembly of FIG. 9 showingthe assembly in the operable orientation;

FIG. 13 is an end view of the spinal implant assembly of FIG. 9;

FIG. 14 is a perspective view of the spinal implant assembly of FIG. 9showing an alternative spacer;

FIG. 15 is a elevation view of a posterior portion of a human spineshowing one of the implant devices of FIG. 9 positioned between adjacentlamina;

FIG. 16 is a top plan view of a human spine showing one of the implantdevices of FIG. 9 positioned between adjacent lamina;

FIG. 17 is a perspective view of a spinal implant assembly according toa third form of the present invention;

FIG. 18 is an exploded perspective view of the spinal implant assemblyof FIG. 17;

FIG. 19 is a side view of the spinal implant assembly of FIG. 17 showingthe assembly in the operable orientation;

FIG. 20 is a top plan view of the spinal implant assembly of FIG. 17showing the guide mechanism;

FIG. 21 is a side view of the spinal implant assembly of FIG. 17 showingthe assembly in the inoperable orientation;

FIG. 22 is a perspective view of an alternate spinal implant assemblyaccording to a third form of the present invention;

FIG. 23 is an exploded perspective view of the spinal implant assemblyof FIG. 22;

FIG. 24 is a is a side view of the spinal implant assembly of FIG. 22;

FIG. 25 is a partial cut-away side view of the spinal implant assemblyof FIG. 22;

FIG. 26 is a top plan view of the spinal implant assembly of FIG. 22;

FIG. 27 is a partial cut-away top plan view of the spinal implantassembly of FIG. 22;

FIG. 28 is a perspective view of a spinal implant assembly according toa fourth form of the present invention,

FIG. 29 is an exploded perspective view of the spinal implant assemblyof FIG. 28;

FIG. 30 is a side view of the spinal implant assembly of FIG. 28 showingthe implant in the inoperable orientation;

FIG. 31 is a side view of the spinal implant assembly of FIG. 28 showingthe implant in the operable orientation;

FIG. 32 is a top plan view of the spinal implant assembly of FIG. 28;

FIG. 33 is a partial cut-away side view of the spinal implant assemblyof FIG. 28; and

FIG. 34-52 are perspective views of the implant tools for inserting aspinal implant assembly of FIGS. 1, 9,17, 22, and 28.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Generally, the present invention provides a spinal stabilization systemfor supporting at least one vertebra of a spine and, more particularly,a laminar region of at least one vertebra. Referring briefly to FIGS.7A, 7B,15,16, a vertebra 1 of a spine generally includes a body 3 and avertebral arch 5 defining a vertebral foramen 15. The vertebral arch 5includes a spinous process 7, a pair of transverse processes 9, alaminar region 11, and pedicle regions 13. The spinous process 7 extendsgenerally directly posterior to the body 3 opposite the vertebralforamen 15. The laminar region 11 is disposed directly behind thespinous process 7 and extends between and interconnects the spinousprocess 7 to the transverse processes 9. The transverse processes 9,therefore, extend generally laterally from the laminar region 11 on eachside of the spinous process 7. The pedicle regions 13 are disposedbetween and interconnect the transverse processes 9 and, therefore, theentire vertebral arch 5 to the body 3. As depicted, the laminar region11 is a generally arch-shaped wall including a superior edge 11 a, aninferior edge 11 b, an anterior surface 11 c and a posterior surface 11d. A system in accordance with the principles of the present inventionprovides support on one or both sides of the central longitudinal axis Lof the spine by engaging the superior and inferior edges 11 a, 11 b ofthe laminar regions 11 of adjacent vertebrae 1, thereby minimizing thepossibility of spinal misalignment caused by the system. Multiplevariations and examples of the present invention will now be describedherein with direct reference to the drawings.

The spinal stabilization device 100, 200, 300, 400, 500 described hereinincludes a first vertebral gripping portion, a second vertebral grippingportion, and an intermediate portion extending therebetween. The spinalstabilization device 100, 200, 300, 400, 500 is interposed between thelaminar regions 11 of adjacent vertebrae 1 a, 1 b. Specifically, thefirst vertebral gripping portion engages the inferior edge 11 b of thelaminar region 11 of the superior vertebra 1 a and the second vertebralgripping portion engages a superior edge ha of a laminar region 11 ofthe inferior vertebra 1 b, while the intermediate portion providessupport therebetween. Thus, the spinal stabilization device 100, 200,300, 400, 500 counteracts any compressive loads applied to the adjacentvertebrae to maintain an appropriate intervertebral spacingtherebetween. Specifically, the compressive loads are transferred fromone of the superior and inferior vertebra 1 a, 1 b through the spinalstabilization system 100, 200, 300, 400, 500 to the other of thesuperior and inferior vertebra 1 a, 1 b. The semi-rigid construction ofthe spinal stabilization system 100, 200, 300, 400, 500, which will bedescribed below, therefore acts as a crutch, stilt or resilient spacerbetween the vertebrae 1 a, 1 b. Further structural details of the spinalstabilization device 100, 200, 300, 400, 500 will now be described.

FIGS. 1-8 depict a spinal implant 100 according to a first form of thepresent invention. The spinal implant 100 includes a first vertebralgripping device 110, a second vertebral gripping device 140 and a rodportion 180. The first and second vertebral gripping devices 110, 140are attached to the rod portion 180, and at least one of the first andsecond vertebral gripping devices 110, 140 is configured to extend alongthe longitudinal axis 184 of the rod portion 180.

As shown in FIGS. 1-3, the first vertebral gripping device 110 includesa first base portion 112 and first hook portion 122 extending from thefirst base portion 112. In one aspect, the first base portion 112 andfirst hook portion 122 are integral. In another aspect of the invention,the connection between the first base portion 112 and first hook portion122 allows for the hook 122 to freely move along one or more axes, suchas with a hinge connection, ball and socket, or other similar connectionmethods (not shown).

The first base portion 112 can optionally include a boss portion 114extending opposite the first hook portion 122. The boss portion 114 isconfigured to be engaged by a transverse member 116 which may be used toconnect two spinal implants 100, the transverse member 116 extendingacross the midline of the spine. The transverse member 116 can be linearor curved, and can be configured to extend through the interspinoustissue or outwardly and around the interspinous tissue. Further, in analternative embodiment, more than one transverse member 116 is used toconnect two spinal implants 100. Preferably, the boss 114 is threaded topermit the transverse member 116 to be securely attached to the bossportion 114 by a securing mechanism, such as a nut.

The first rod portion 180 extends laterally from the first vertebralgripping device 110 along a rod axis 184. In one aspect, the first baseportion 112 is integral with the rod portion 180. In another aspect, therod portion 180 is connected to the first base portion 112 by any knownmethod. As an example (not shown), the first base portion 112 includes athroughbore configured to accept the rod portion 180 therein. The rodportion 180 is securable within the throughbore by any known securingmechanism such as a set screw or pin.

In one aspect, the rod portion 180 includes an annular outer edgeconfigured to permit rotation of one or both of the first and secondvertebral gripping device 110, 140 therearound. In a preferredembodiment, as shown in FIG. 1, the rod portion 180 has a non-annularsurface 186 to restrict rotation around the rod portion 180.

As shown in FIG. 6, the first hook portion 122 has a first width 124that is less than the width 118 of the first base portion 112. The firsthook portion 122 is offset from the first base portion 112 and the rodportion 180. Preferably, the first hook portion 122 is offset so that afirst side surface 120 of the first body portion 112 is in line with afirst side surface 126 of the first hook portion 122. Preferably, thewidth 124 of the first hook portion 122 does not extend beyond thecenter 181 of the longitudinal axis 184 of the rod member 180.

The first hook portion 122 further includes a first seat portion 130 anda tapered distal end portion 123. The distal end portion 123 is taperedto ease in insertion and to minimize the amount of material that isintroduced behind the lamina while maintaining the overall strength ofthe first hook portion 122. The first seat portion 112 has a generallyC-shape 131. In one embodiment, the seat portion 130 has a contouredsurface configured to engage and extend around the lamina. Preferably,the upper and lower walls 132, 133 of the first seat portion 130 extendacross the width 137 of the first seat portion 130 at an upward angle134 relative to the rod axis 184. The angle 134 of incline ispredetermined to conform to the geometry of the individual lamina beingengaged.

Further, the rear wall 135 of the first seat portion 130 is taperedacross the width 137 of the first seat portion 130 such that the rearwall 135 has a first width 138 at one side of the first seat portion 130and has a second width 139 shorter than the first width 138 on the otherside of the first seat portion 130. Preferably, the rear wall portion130 has the shorter, second width 139 on the same side of the seatportion 130 as the lowermost part of the upper and lower wall portions137, 133. As with the angle 134 of the taper, the rear wall portion 135of the first seat portion 130 is configured to conform to the geometriesof the individual lamina being addressed.

The second vertebral gripping device 140 includes a second hook portion142 and a second body portion 152, the second hook portion 142 extendingfrom the second body portion 152. The second body portion 152 isconfigured to engage the rod portion 180 and permit the second bodyportion 152 to translate along the rod portion 180. As shown in FIG. 2,in one embodiment a rod accepting throughbore 154 extends through thesecond body portion 152. In one embodiment, the rod acceptingthroughbore 154 is configured to snugly engage the rod portion 180. Inan alternative embodiment, as shown in FIG. 6, the rod acceptingthroughbore 154 is configured to permit the rod portion 180 to adjustlaterally and vertically a predetermined amount to allow the second hookportion 142 to not interfere with the first hook portion 122′ when thespinal implant 100 is positioned in the compact or inoperableorientation, and to aid in insertion and engagement of the spinalimplant 100 with the lamina. The second body portion 152 is secured tothe rod portion 180 by a securing mechanism 156. As an example, as shownin FIGS. 1 and 2, the body portion 152 includes a threaded throughbore158 extending through the body portion 152 to the rod acceptingthroughbore 154. The threaded throughbore 158 is configured to accept aset screw 160 therein, the set screw 160 being operable to engage andurge the rod portion 180 against the rod accepting throughbore 154,thereby restricting the movement of the second hook body portion 142along the rod portion 180.

The second hook portion 142 is connected to and extends from the secondbody portion 152. In one aspect, the second hook portion 142 is integralwith the second body portion 152 as shown in FIGS. 1-4. In analternative aspect, the second hook portion 142 is connected to thesecond body portion 152 so as to allow for the hook 142 to freely movealong one or more axes, such as with a hinge connection or ball andsocket. By allowing the second hook portion 142 to freely move inrelation to the second body portion 152 the spinal implant 100 can beadjusted to fit the lamina upon insertion and engagement.

The second hook portion 142 extends downward and away from the secondbody portion 152. The second hook portion 142 includes a straightportion 144 and a curved portion 146 having a second distal end 148. Thesecond straight portion 144 extends downwardly and away from the secondbody portion 152 at a predetermined angle 150 more than 0 degrees andless than 90 degrees, the predetermined angle 150 depending on the sizeand geometry of the lamina to be engaged. The second curved section 146extends from the end of the second straight section 144, and is taperedalong a portion thereof toward the second distal end 148. The secondcurved section 146 is tapered to minimize the size of the implant 100that is positioned around the lamina while maintaining the desiredstrength and durability of the spinal implant 100.

The second hook portion 142 extends normally from the rod portion 180 asecond distance 168 further than the distance 125 the first hook portion122 extends normally from the rod portion 180. The second distance 168is predetermined based on the orientation of the lamina to be engaged.Generally, within the spine the superior edge of the lamina is set backfurther than the inferior edge of the lamina. By extending the secondhook portion 142 further than the first hook portion 122 to account forthe setback, the spinal implant 100 maintains its orientation extendingalong the spine and does not interfere with other portions of the spine,such as the lamina, spinous processes, and transverse processes.

The second hook portion 142 further includes a second seat portion 162for engaging the lamina. As shown in FIG. 2, the second seat portion 162has a generally C-shape 164. Similar to the first seat portion 130, inone embodiment the second seat portion 162 extends upwardly across thewidth 166 of the second seat portion 162 at an angle relative to the rodaxis 184 to accommodate the geometry of the lamina.

The second hook portion 142 is preferably offset from the second bodyportion 152 and the rod portion 180. The offset of the second hookportion 142 is predetermined to minimize interference between the firstand second hook portions 122, 142 and permit the hook portions 122, 142to laterally overlap when the spinal implant 100 is in the compactorientation 101 as shown in FIG. 4. Further, the distance 169 that thesecond hook portion 142 extends along the rod axis from the second bodyportion 152 is predetermined so that when the spinal implant 100 is inthe compact orientation 101, the first and second hook portions 122, 142overlap while the first and second body portions 112, 152 are adjacentor abut along the rod portion 180. Preferably, the first and second hookportions 122, 142 overlap such that the overall profile of the first andsecond hook portions 122, 142 in the compact orientation 101 isapproximately the same as the overall profile of the first hook portion122, thereby minimizing the distance the lamina would need to bedistracted for insertion of the spinal implant 100.

Preferably, the first hook body portion 122 is configured to engage theinferior surface of a first lamina, the second hook body portion 142configured to engage the superior surface of a second lamina, the firstlamina being located directly above the second lamina along the spine.

FIGS. 9-16 depict a spinal implant 200 according to a second form of thepresent invention. In another aspect of the invention, the spinalimplant 200 is configured to self adjust to the contour of the vertebraewithin an interlaminar space when translated from the compactorientation 201 to the operable orientation 202. The spinal implant 201includes a first body portion 210, a second body portion 240 and a rodportion 270 extending tangentially from the second body portion 240. Thesecond body portion 240 is connected to the rod portion 270. In oneembodiment, the second body portion 240 is integral with the rod portion270. In an alternative embodiment, the second body portion 240 issecured to the rod portion 270 by a securing mechanism, such as a setscrew (not shown) and may be translatable along the rod portion 270.

The first body portion 210 includes a first hook portion 212 comprisingtwo first lateral surfaces 214, a first rear surface 216, a firstforward surface 218 and a first inferior surface 220. The first bodyportion 210 includes a width 222, a depth 224, and a height 226. Thefirst body portion 210 further includes first seat portion 227 forengaging an inferior portion of a lamina, the first seat portion 227including a recessed groove that extends across a portion of one of thefirst lateral surfaces 214, across the first forward surface 218 andacross the other first lateral surface 214. The recessed groove furtherextends from the first forward surface 218 toward the first rear surface216. The recessed groove 228 extends across the first hook portion 212at an angle 230 relative to the rod axis 274 between the lateralsurfaces 214. The angle 230 is selected to accommodate the shape andconfiguration of the inferior lamina surface. Further, in alternativeembodiments, the recessed groove can includes varying radii of curvatureand slopes of curvature. In a further embodiment, the radii of curvatureand slope of the curves may vary across between the lateral surfaces 214of the first body portion 210 and as the recessed groove extends fromthe forward surface 218 to the rear wall 216. Preferably, as shown inFIGS. 11, 12, the portion of the rear wall 216 defining the seat 227tapers across the width 222 of the first body portion 210. Additionally,as the seat 227 extends across the width 222 of the first body portion210 the seat 227 extends upwardly along the height 226 of the first bodyportion 210.

The first body portion 210 includes a rod accepting portion 242configured to permit the first body portion 210 to translate along therod portion 270. In one embodiment the rod portion 270 has an annularsurface to permit the first body portion 210 to rotate around thelongitudinal axis 274 of the rod portion 270. In a preferred embodimentthe rod portion 270 has a non-circular surface 272 to restrict rotationof the first body portion 210 around the rod portion 270.

The second body portion 240 includes a second hook portion 244comprising two second lateral surfaces 246, a second rear surface 248, asecond forward surface 250 and a second inferior surface 252. The secondbody portion 240 includes a width 254, a depth 256, and a height 258.The second body portion 240 further includes second seat portion 260 forengaging a superior portion of a lamina, the second seat portion 260being defined by an recessed groove 262 extending across a portion ofthe rear surface 248, one of the lateral surfaces 246, the forwardsurface 250 and a portion of the other lateral surface 246. Further, therecessed groove 262 extends from the second forward surface 250 towardthe second rear surface 248.

In one embodiment, as shown in FIG. 13, the recessed groove 262 extendsacross the second hook portion 240 at an angle 264 relative to the rodaxis 274 between the second lateral surfaces 246. The angle 264 isselected to accommodate the shape and configuration of the superiorlamina surface.

Preferably, as shown in FIGS. 9, 11 and 12, the portion of the rear wall248 defining the seat 260 tapers across a portion of the width 254 ofthe second body portion 240 such that the rear wall portion 248 does notextend the width 254 of the second body portion 240 along at least aportion of the second seat portion 260. In one embodiment, as shown inFIG. 12, as the seat 260 extends across the width 254 of the second bodyportion 240 the seat 260 extends upwardly along the height 258 of thesecond body portion 240.

In one embodiment, the second seat portion 260 includes a contouredconfigured surface to self adjust to the contour of the superior portionof a lamina when engaged in the operable orientation. In one embodiment,the contoured surface includes varying radii of curvature and slopesextending across the seat portion 260. The radii of curvature and slopesof the contoured surface can vary between the lateral surfaces 246, fromthe front surface 250 toward the rear surface 248, and along the heightof the seat portion 260.

The spinal implant 200 includes a compact or inoperable orientation 201and an operable orientation 202, each of which is defined by thelocation of the first body portion 210 and the second body portion 240on the rod portion 270. The compact orientation 201 is defined by thefirst body portion 210 being translated toward the second body portion240 such that the first and second rear surfaces 216, 248 of the firstand second body portion 210, 240 are adjacent. The operable orientation202 is defined by moving at least the first body portion 240 along therod portion 270 a predetermined distance to engage the lamina. As thefirst and second body portions 210, 240 engage the lamina, theconfiguration of the first and second seats 227, 260 urge the implant200 to the appropriate implantation orientation for ease of insertion.

Upon translation of the spinal implant 200 to the operable orientation202, the spinal implant includes a securing mechanism 280. The securingmechanism is configured to maintain a desired distance between the firstand second body portion 210, 240, and can be accomplished by any knownmeans, such as set screws, tapered sleeves, and pins. As shown in FIGS.9 and 12, a spacer 282 configured to be inserted on the rod portion 270can be inserted between the first and second body portions 210, 240. Thespacer can be rigid or resilient depending on the application. Anotherexemplary securing mechanism 280 is shown in FIG. 14, where the securingmechanism 280 is a spring member 286. The spring member 286 includes apair of sleeves 288 which are configured to be accepted on the rodportion 270. The sleeves 288 are connected by at least two arms 290extending between the sleeves 288. In one embodiment, the arms 290 arerigid. In a preferred embodiment, the arms 290 are resilient inconstruction.

FIGS. 17-27 depict spinal implants 300, 400 according to a third form ofthe present invention. In one embodiment, a spinal implant 300, 400includes a guide mechanism. The spinal implant 300, 400 includes a guidemechanism to transition the implant 300, 400 from the compact orinoperable orientation to the operable orientation. The guide mechanismis configured to permit the implant 300, 400 to transition in apredetermined direction, whether it is linear or rotational. Preferably,the guide mechanism includes a locking mechanism to restrict themovement in the predetermined direction. In one aspect, the lockingmechanism allows for movement only toward the operable orientation andrestricts movement toward the compact orientation. The locking mechanismcan be any known locking mechanism, such as a ratcheting mechanism.Generally, the ratcheting mechanism includes teeth portions andcorresponding teeth engagement portions. Preferably, the teeth portionshave a camming surface which extends outwardly from the guide mechanismat an angle less than 90 degrees and a stop surface which extends fromthe guide mechanism at an angle of about 90 degrees. The teethengagement portion includes corresponding second camming surfaces whichcorrespond to the camming surface of the teeth portions to permit thesecond camming surface to shift along the second camming surface towardthe operable orientation. The teeth engagement portion also includes acorresponding second stop surface which is configured to engage the stopsurface of the teeth portion and restrict movement toward the compactorientation.

In one aspect of the third form of the invention, as shown in FIGS.17-21, the spinal implant 300 includes a first engagement portion 310, asecond engagement portion 340 and a pivot mechanism 360. The spinalimplant 300 further includes an operable orientation 302 wherein thefirst and second engagement portions 310, 340 extend in oppositedirections and a compact orientation 302 wherein the first and secondengagement portions 310, 340 are adjacent one another.

The first engagement portion 310 includes a first seat portion 312 forengaging the lamina and a first arm 314 and second arm 316 extendingopposite the first seat portion 312. The first arm 314 extends parallelto the second arm 316, each arm 312, 314 having a throughbore 320extending therethrough for accepting a pivot mechanism 360 therein.

The second arm 316 includes a locking arm 322 having a teeth engagingportion 324 at the distal end 333 thereof. The teeth engaging portion324 extends from the locking arm 332 toward the first arm 314 and beyondthe inner surface 337 of the second arm 316. The locking arm 322 extendsalong the outer edge 338 of the second arm 316 and is defined by acut-out portion 332 of the second arm 316 along the distal end 333 andlength 334 of the locking arm 322. Further, the locking arm 322 isconfigured to be shifted away from the first arm 314 upon theapplication of force thereon to disengage the teeth engaging portion 324from the teeth portion 346 allowing the spinal implant 300 to betransitioned back to the compact orientation 301. In one embodiment, thelocking arm 322 has a width 335 that does not extend the width 318 ofthe second arm 316 thereby permitting the locking arm 322 to shiftwithin the space defined by the width 318 of the second arm 316. In afurther embodiment, the second arm 316 includes two or more locking arms322 for engaging the teeth portions 346.

The second engagement portion 340 includes a second seat portion 342 forengaging the lamina, and first and second arms 345, 354 extendingopposite the second seat portion 342. The first arm 345 extends parallelto the second arm 354, each arm 345, 354 having an throughbore 358extending therethrough for accepting the pivot mechanism 360. The firstarm 345 includes the teeth portion 346, which extend around a portion ofthe throughbore 358 and toward the second arm 354. In one embodiment,the teeth portion 346 extends circumferentially around the throughbore358.

The first and second engagement portions 310, 340 are configured so thatthe first arm 345 of the second engagement portion 340 is receivablebetween the first and second arms 314, 316 of the first engagementportion 310, and the second arm 316 of the first engagement portion 310is receivable between the first and second arms 345, 354 of the secondengagement portion 340.

The pivot mechanism 360 extends through the throughbores 320, 358 in thefirst and second arms 312, 314, 345, 354 of the first and secondengagement portions 310, 340. In one embodiment, the pivot mechanism 360includes a first member 362 including a pivot pin portion 364 configuredto extend through the throughbores 320′, 358 and a head portion 368configured to be larger than the throughbores 320, 358 to restrictmovement of the rod portion 364. The pivot mechanism 360 furtherincludes a securing member 370 to be attached at the distal end 366 ofthe pivot pin portion 364, such as a nut. Preferably, the throughbores320, 358 and pivot pin portion 364 have smooth, annular surfaces topermit free rotation.

As the first and second engagement portions 310, 340 pivot around thepivot mechanism 360 from the compact orientation 301 toward the operableorientation 302, the camming surface 348 of the teeth portion 346 engagethe corresponding second camming surface 326 of the teeth engagingportion 324 of the locking arm 322, thereby urging the locking arm 322away from the teeth portions 346. When the teeth engaging portion shiftspast the teeth portion 346 and thereby 324 ceases to be engaged with theteeth portion 346 the locking arm 322 shifts back toward the teethportion 346.

The stop portions 328, 349 of the teeth portion 346 and teeth engagingportion 324 are configured to engage one another and block pivoting ofthe first and second engagement portions 310, 340 toward the compactorientation. As described above, in one embodiment the locking arm 322is configured to disengage the teeth portion 346 upon the application offorce to the locking arm 322 urging the locking arm 322 away from theteeth portion 346.

The spinal implant 300 can be further secured in the operableorientation 302 by any of the known methods. Further, in one embodimentthe spinal implant 300 includes a band portion 380 extending from thefirst engagement portion 310 to the second engagement portion 340.Preferably, the band portion 380 is configured to be secured at eachend, such as by a loop or hook portion 382. The securing mechanismfurther includes a pair of band hooks 384 extending from the first andsecond engagement portions 310, 340 configured to be engaged by the loopor hook portions 382. Further, one of the arms 312, 314, 345, 354 of thefirst and second engagement portion 310, 340, such as the first arm 345of the second engagement portion 340, includes a sleeve 386 configuredto accept the band 380 therein to guide and hold the band 380 in placewhile the spinal implant 300 is inserted and shifted to the operableorientation 302. The band 380 may be rigid or resilient pending thedesired operation.

In another aspect of the third form of the invention, as shown in FIGS.22-27, the spinal implant 400 includes a box portion 401, a secured hook420, a movable hook 450 and a securing block 480.

The box portion 401 includes end walls 402, 403, sidewalls 407, a lowerfloor surface 404, and an open upper end 413. The lower floor surface404 includes a first aperture 405 extending therethrough adjacent theend wall 402 for receiving secured hook 420 and a slot 406 extendingacross the lower surface floor 404 for receiving and accommodatingmovable hook 450.

Secured hook 420 includes a hook connector 421 and a hook portion 435connected to the hook connector 421. The hook connector 421 includes ahead 422 and an elongate body 427, the head 422 configured to bereceived within the box portion 401 and the elongate body 427 configuredto extend through the first aperture 405. The elongate body 427 has apredetermined width 428 and depth 430 to allow the elongate body toextend through the first aperture 405 such that the elongate body 427 isrotatable and movable within the first aperture 405. Further, the head422 is sized larger than the first aperture 405 so that the head 422prevents the hook connector 421 from shifting completely through thefirst aperture 405.

The elongate body 427 extends a predetermined length 429 and includes anindentation portion 431 extending perpendicular the longitudinal axis432 of the elongate body 427 and positioned a predetermined distancefrom the distal end of the elongate body 427. The elongate body 427 isconfigured to be accepted within an aperture 437 extending through theupper surface 436 of the hook 435. The hook 435 further includes anindention engaging portion 438 configured and sized to accept and engagethe indention 431 of the elongate body 427, thereby securing theelongate body 427 with the hook 435.

The hook 435 further includes a curved end portion 439 and a seat 440for engaging the lamina. In one embodiment, the hook includes a rearsurface 441 having at least one indentation 442 therein for beingcontacted and accepting the rear edge 453 of the movable hook 450.

The movable hook 450 includes a hook portion 451 and a translatingportion 465. The hook portion 451 includes a seat 452 for engaginglamina, a flat upper surface 455 configured to extend below the end wall403 of the box portion 401 when the movable hook 450 is in the operableorientation, and a rear edge 453 having a convex shape 454. In oneembodiment, the convex shape 454 of the rear edge 453 is configured tobe accepted by the indentations 442 of the rear surface 441 of thesecure hook 420.

The translating portion 465 of the movable hook 450 includes a firstbottom surface 466, a second bottom portion 468, an upper surface 478,and a pair of end surfaces 477, 477 a. The second bottom portion 468extends a distance 467 from the first bottom surface 466, and isconnected to the hook portion 451 by a rigid or pivotable connection.The distance 467 is predetermined based on the height of the head 422 ofthe secured hook 420. By having an elevated first bottom surface 466,the movable hook 450 is able to translate across the length of the boxportion 401 because, in the compact orientation 498, the first bottomsurface 466 is in contact with the upper surface 423 of the head 422,rather than the end surface 477 coming into contact with the head 422.

In one embodiment, the box portion 401 is configured to maintain themovable hook 450 within the box portion 401 once inserted. In oneembodiment, the box portion 401 includes a pair of runners 410 extendingalong a portion of the upper edge of the sidewalls 407. The runners 410are separated by a width 412 and include a tapered lower end 411. Thewidth 412 between the runners 410 is predetermined to be less than thewidth of the translating portion 465, thereby maintaining the movablehook 450 within the box portion 401 when the translating portion 465 islocated under the runners 410. The translating portion 465 includestapered upper end edges to assist in the insertion of the movable hook450 in the box portion 401.

The box portion 401 and movable hook 450 provide for the guide mechanism418 and the locking mechanism 419. As shown in FIGS. 22-24, the boxportion 401 includes sidewalls 407 having a pair of cutouts 409 on eachsidewall 407 which are connected to the box portion 401 on one end, asshown in FIG. 24.

Further, on the inner surface 408 of the sidewalls 407 there are aplurality of teeth portions 414. The teeth portions 414 include acamming surface 415 facing the end wall 402 and a stop surface 416facing the end wall 403. The stop surface 416 extends from the sidewall407 at an angle of about 90 degrees, preferably 90 degrees. The cammingsurface 415 extends from the sidewalls 407 at an angle less than 90degrees. In one embodiment, the camming surface 415 extends at an anglebetween 30 and 60 degrees. In addition, the movable hook 450 includescorresponding forward hook teeth portions 469 and rear hook teethportions 472, each having a camming surface 470, 473 configured to facethe end wall 403 and a stop surface 471, 474 configured to face end wall402. The stop surface 471, 474 extends from the translating portion 465at an angle of about 90 degrees, preferably 90 degrees. The cammingsurface 470, 473 extends from the translating portion 465 at an angleless than 90 degrees. In one embodiment, the cammings surface 470, 473extends at an angle between 30 and 60 degrees.

As the movable hook 450 translates along the box portion 401, thecamming surfaces 415 engage the hook camming surfaces 470, 473. Thecutouts 409 are urged outward until the camming surfaces 470, 473translate past the camming surface 415, wherein the cutouts 409 shift totheir natural position. This process is continued until the movable hook450 is in the desired operable orientation 499.

When the movable hook 450 and secured hook 420 are under loadconditions, such as when inserted between adjacent lamina, the stopsurfaces 416 will engage the stop surfaces 471, 474. The engagement ofthe stop surfaces 416 with the stop surfaces 471, 474, will resisttranslation of the movable hook 450 toward the compact orientation 498.

In one embodiment the cutouts 409 can be urged outwardly by an externalapplication of force to permit the securing surfaces 416 to bypass thesecuring surfaces 471, 474 and allow the movable hook 450 to betranslated to the compact orientation 498.

The securing block 480 is configured to be inserted into the box portion401 when the movable hook 450 is in the operable orientation 499 tofurther resist translation of the movable hook 450 toward the compactorientation 498. The securing block 480 has a width 481 greater than thespace 412 between the runners 410 of the box portion 401. The securingblock 480 also has a predetermined length 483 based on the predeterminedoperable orientation 499 of the movable hook 450. An example of length483 includes the range of about 1 mm to about 8 mm. In addition, thesecuring block 480 includes a first bottom surface 484, a second bottomsurface 485 and a bottom step 486 therebetween. The bottom step 486 isconfigured to permit the first bottom surface 484 to contact the floor404 of the box portion 401 while also allowing the second bottom surface485 to contact the upper surface 423 of the head 422 of the secured hook420. The length 483 of the securing block 480 is sized so that thesecuring block 480 engages the end wall 402 of the box portion 401 andthe end surface 477 of the translating portion 465 of the movable hook450.

The securing block 480 further includes a pair of tapered bosses 491extending from either end of the securing block 480 to secure thesecuring block 480 between the movable hook 450 and the end wall 402 ofbox portion 401. The tapered bosses 491 are preferably cut-out on thesides 492 and rear 493 to permit limited movement of the tapered bosses491. The end wall 402 of the box portion 401 includes a correspondingdetent 417 to accept one tapered boss 491, while the end surface 477 ofthe movable hook 450 has a similar corresponding detent 476 to acceptthe other tapered boss 491.

In one embodiment, the sidewalls 487, 488 include a pair of steps 489therein to aid in insertion of the securing block 480. The steps 489have a width 490 less than the width 412 between the runners 410 of thebox portion 401. Therefore, the steps 489 permit the insertion of asecuring block 480 having a length 483 which extends from the end wall402 beyond the start of the runners 410.

FIGS. 28-33 depict a spinal implant 500 according to a fourth form ofthe present invention. The spinal implant 500 includes a vertebralengaging arm 510, a second vertebral engaging arm 540, a generallyU-shaped body 570 and a pivoting mechanism 590.

The first vertebral engaging arm 540 includes a first engagement portion520, a spacer portion 511 and a pair of spaced arms 530. The firstengagement portion 520 includes a semicircle-shaped seat 521 forcontacting and engaging one of the adjacent lamina. The first engagementportion 520 extends from a distal end 512 of the spacer portion 511. Inone embodiment, the spacer portion 511 includes an insertion throughbore514 extending across the width 516 of the spacer portion 530 andconfigured to be engaged by an inserter tool. Preferably, the spacerportion 520 further includes a first tapered portion 515 surrounding theinsertion throughbore 514 to aid in engaging the insertion tool.

Extending from the proximal end 513 of the spacer portion 511 are thepair of spaced arms 530. The spaced arms 530 have an annular distal end531 and are offset from the spacer portion 511 such that the arms 530extend beyond the width 516 of the spacer portion 511. The spaced arms530 have a pair of corresponding pivot throughbores 533 configured toaccept the pivot mechanism 590 therein. In a preferred embodiment, thethroughbores 533 include a tapered edge therearound.

The second vertebral engaging arm 540 includes a second engagementportion 541, a spacer portion 545 and a centered arm 558. The secondengagement portion 541 includes a semicircle-shaped seat 542 forcontacting and engaging the other of the adjacent lamina. The secondengagement portion 541 extends from a distal end 546 of the spacerportion 545. The spacer portion 545 includes an insertion throughbore549 extending across the width 548 of the spacer portion 545 andconfigured to be engaged by an inserter tool. The spacer portion 545further includes a first tapered portion 550 surrounding the insertionthroughbore 549 to aid in engaging the insertion tool.

Extending from the proximal end 547 of the spacer portion 545 is thecentered arm 558. The centered arm 558 is defined by a pair of steps 560positioned on either lateral surface 552 of the second arm portion 545.The steps 560 extend across the lateral surface 552 from the upper edge554 of the second vertebral engaging arm 540 toward the lower edge 556and at an angle 562 extending toward the distal end 546, as shown inFIGS. 29, 31, 33. The depth of the steps 560 is predetermined so thatthe centered arm 558 is receivable between the spaced arms 530 of thefirst vertebral engaging arm 510. The centered arm 558 includes anannular end portion 564 and a second pivot throughbore 566 extendingtherethrough configured to accept the pivot mechanism 590 therein.

The U-shaped body 570 includes a base portion 571 and a pair of spacedside arms 580. The spaced side arms 580 extend in parallel from thebottom surface 572 of the base portion 571 and include annular-shapeddistal ends 581. The spaced side arms 580 are separated by a distance582 sufficient to receive the spaced arms 530 of the first vertebralengaging arm 510 therebetween. Further, the spaced side arms 580 includethird pivot throughbores 583 extending therethrough and configured toaccept the pivot mechanism 590 therein, the third pivot throughbores 583further corresponding to the pivot throughbores 533 of the spaced arms530 of the first vertebral engaging arm 510 and second pivot throughbore566 of the centered arm 558 of the second vertebral engaging arm 540. Aswith the first and second vertebral engaging arms 510, 540, the sleevearms 580 preferably include rounded edges to minimize damaging theadjacent tissue when inserted between lamina in the spine.

The base portion 571 includes a stop portion 572. In one embodiment, thestop portion 572 is defined by a bottom surface 572, the bottom surface572 configured for contacting the spaced arms 530 and center arms 558.In addition, the base portion 571 further includes slotted side surfaces573 for being engaged by the inserter tool, rounded end surfaces 574 andan upper surface 575. The base portion 571 further includes a securingmechanism 576. In one embodiment, as shown in FIG. 29, the base portion571 includes a threaded throughbore 577 extending from the top surface575 to the bottom surface 572. The threaded throughbore 577 isconfigured to receive a set screw 578 therein, the set screw 578configured to engage the centered arm 558 and spaced arms 530 torestrict movement of the centered 558 and spaced arms 530 when in theoperable configuration.

The pivot mechanism 590 is configured to extend through the pivotthroughbores 533, second pivot throughbore 566 and third pivotthroughbores 583 and provide a structure around which the first andsecond vertebral engaging arms 510, 540 could pivot. In one embodiment,as shown in FIG. 29, the pivot mechanism 590 includes a bushing 591 anda pin 597. The bushing 591 is configured to extend through the pivotthroughbores 533, second pivot throughbore 566 and third pivotthroughbores 583. The bushing 591 further includes an enlarged headportion 592 for engaging an outer surface 584 of a sleeve arm 590 and ahollow portion 593 extending along the longitudinal axis 594 of thebushing 591 and configured to receive the pin 597 therein. The pin 597includes an oversized pin head 598 configured to engage a second outersurface 585 of the sleeve arm 580. The pin 597 and bushing 591 can besecured in any manner known in the art, including a threaded connection,pins or set screws, for example.

Upon assembly of the spinal implant 500, the first and second vertebralengaging arms 510, 540 are free to pivot around the pivot mechanism 590.The angle 562 of the steps 560 on the second vertebral engaging arm 540provides the spaced arms 530 with additional space to occupy therebypermitting the first and second vertebral engaging arms 510, 540 to bemoved adjacent one another. By moving the steps 560 toward the secondseat portion 542 and by optimizing the angle 562 of the steps 560, thefirst and second vertebral engaging arms 510, 540 are able to bepositioned closer one another in the compact orientation 600.

The spinal implant 500 is adjustable between a compact orientation 600and an operable orientation 601. Upon inserting the spinal implant 500between adjacent lamina, the first and second vertebral engaging arms510 can be extended from the compact orientation 600 to the operableorientation 601. Once the first and second vertebral engaging arms 510,540 are extended to the operable orientation 601, the set screw 578 isinserted and tightened in the sleeve threaded throughbore 577 of thesleeve body portion 571 until the set screw 578 engages the first andsecond vertebral engaging arms 510, 540 and restricts the movements ofthose vertebral engaging arms 510, 540.

While the spinal implants 100, 200, 300, 400, 500 described above weredirected toward insertion between adjacent lamina, the spinal implants100, 200, 300, 400, 500 could be inserted in other portions of thespine. Alternatively, the spinal implant could function to relievepressure on the spinal nerves branching off of the spinal cord due tospinal stenosis when implanted between the transverse processes. Thespinal implants would provide distraction, thus expanding the spinalcanal volume to reduce pressure on the spinal cord or spinal nervesbranching off of the spinal cord. The placement of the implants near themiddle of the span of the transverse process will tend not to impinge onthe spinal nerves branching off of the spinal cord under the superioredge of the transverse process, yet not create a structural failure inthe dense cortical bone of the transverse process itself.

Further, the placement of the implant on the transverse processes wouldprovide equivalent decompress to the spinal cord or spinal nervesbranching off of the spinal cord without risking damage to the spinalcord itself and the attendant paralysis to all inferior nerves below thepoint of implantation. The spinal nerves branching off of the spinalcord under the superior edge of the transverse process are under muchless risk of damage during implantation on the transverse processbecause the spinal nerves can shift along with surrounding tissue andwill not be pinched between the implant and the bone of the vertebrae.The loading on the transverse processes would be minimal because onlyminimal distraction and deflection of the structures of the spine arerequired with stenosis patient where typically the intervertebral discshave only subsided and have not failed. Placement of implants laterallyon both transverse processes would limit lateral bending but minimallyreduce extension and flexion.

The implant devices 100, 200, 300, 400, 500 of the present invention maybe fabricated from any suitable materials having desirable strength andbiocompatibility. Suitable materials may include, for example,biocompatible metals and related alloys (such as titanium and stainlesssteel), shape memory metals (such as Nitinol), biocompatible polymers(including, for example, materials of the polyaryletherketone familysuch as PEEK (polyetheretherketone), PAEK (polyaryletherketone), PEK(polyetherketone), PEKK (polyetherketoneketone), PEKEKK(polyetherketoneetherketoneketone), PEEKK (polyetheretherketoneketone),and PAEEK (polyaryletheretherketone), filled materials (such as carbonor glass fiber-reinforced materials), bone substitute materials (such ashydroxyapatite and tricalcium phosphate), composite materials, and/orany combination of the above.

In one form, the implant devices are formed of a PEEK-type material. Inanother from, the implant device may be formed, in whole or in part, orcoated with a calcium phosphate ceramic bone substitute such ashydroxyapatite, tricalcium phosphate, and/or mixtures thereof.Particularly preferred hydroxyapatite and tricalcium phosphatecompositions include those disclosed in, for example, U.S. Pat. No.6,013,591, U.S. Pat. No. RE 39,196, and U.S. Patent ApplicationPublication No. 2005/0031704, which are hereby incorporated in theirentirety herein. Coating with the calcium phosphate ceramics can beachieved by any known method, including dip coating-sintering, immersioncoating, electrophoretic deposition, hot isostatic pressing, solutiondeposition, ion-beam sputter coating and dynamic mixing, thermalspraying techniques such as plasma spraying, flame spraying andhigh-velocity oxy-fuel combustion spraying. In one preferred embodiment,hydroxyapetite coating is achieved by plasma spraying.

In yet another form, the implant device may be formed of a PEEK-typematerial and coated with such a bone substitute material. In yet anotherform, the implant device may be formed, in whole or in part, coatedwith, injected with, incorporate, and/or retain a bone growthstimulating composition such as the bioactive hydrogel matrix described,for example, in U.S. Pat. No. 6,231,881, U.S. Pat. No. 6,730,315, U.S.Pat. No. 6,315,994, U.S. Pat. No. 6,713,079, U.S. Pat. No. 6,261,587,U.S. Pat. No. 5,824,331, U.S. Pat. No. 6,068,974, U.S. Pat. No.6,352,707, U.S. Pat. No. 6,270,977, U.S. Pat. No. 5,614,205, U.S. Pat.No. 6,790,455, U.S. Pat. No. 5,922,339, and U.S. Patent ApplicationPublication No. 2005/0118230, which are hereby incorporated in theirentirety herein. Another example of a composite for the spinal implantis a composition formed from PEEK coated with hydroxyapatite (HA) withno significant alteration to the biocompatibility profile to the PEEK.The HA coating provides sufficient mechanical bond strength to allow theHA to sufficiently adhere to the PEEK support structure which forms theimplant body without having to melt PEEK to obtain sufficient bondstrength. The HA coated PEEK now preserves the biocompatibility profileof the PEEK and yet still provides a bioactive interface for improvedbiologic integration between the implant and patient. The HA coatingprovides sufficient bioactivity to allow an interface between theadjacent bone and HA to allow bone ingrowth, ongrowth, or otherwise actas an osteoconductive agent, i.e. fusion, by the patient's body.

A spinal implant inserter apparatus is shown in FIGS. 34-52. Theinserter apparatus 2001 generally securely engages a spinal implant 100,200, 300, 400, 500, and is configured to distract the spine and implantthe spinal implant device 100, 200, 300, 400, 500 simultaneously.

The inserter apparatus 2001 includes the first gripping portion 2101,the second gripping portion 2201, the parallel-action assembly 2301, thehandles 2401, the ratchet bar 2501, the screw driver 2601, thecounter-torque device 2651, the nut driver 2701, and the counter-torquehandler 2751 shown together in FIG. 44.

The first gripping portion 2101 includes two flanges 2105 as shown inFIG. 48, and a groove 2103 shown in FIG. 46, the groove located at thedistal end of the inserter apparatus 2001 for providing a fixed anchorpoint for the spinal implant 100, 200, 300, 400, 500. The first grippingportion 2101 allows for the mechanical engagement of the spinal implant100, 200, 300, 400, 500 and the release of the spinal implant 100, 200,300, 400, 500 upon completion of the implantation process as describedbelow.

The first and second gripping portion 2101 & 2201 are canted at an angleK of approximately 36 degrees as shown in FIG. 46. As shown in FIG. 47,the canting allows a surgeon to look directly into the incision to seethe progress of the implantation without the insertion tool itselfobstructing the surgeon's vision. In addition, the first and secondgripping portion 2101 & 2201 are preferably made of 17-4 stainlesssteel. The 17-4 stainless steel is preferably low friction chromecoated, hardened, and electropolished to allow the spinal implants 100,200, 300, 400, 500 to easily connect and disconnect to the flanges 2105.

The second gripping portion 2201 is composed of three fingers 2203 and acentrally located through bore 2205. The fingers 2203 provide for a wayto release ably connect the spinal implants 100, 200, 300, 400, 500 tothe insertion tool 2001 as previously described. The through bore 2205provides a guide for the screw driver 2601 in order to preventinadvertent injury to the spinal cord or nerves when driving the driver2601 as shown in FIG. 44.

The parallel-action assembly 2301 is composed of multiple links 2303joined together for providing parallel movement, i.e. linear rather thanarcuate translation. The parallel-action assembly 2301 functions toconvert arcuate translation of the handles 2401 to parallel translation.For example, the first and second gripping portions 2011 & 2201 movetogether and away from one another while remaining parallel. The links2303 overlap one another and shift within slots 2305 as shown in FIGS.47 & 48 to create parallel movement of the first and second grippingsections 2101 & 2201. Pins used to connect the links 2303 provide pivotpoints for the parallel-action assembly 2301 are preferably clearplastic to prevent galling and smooth movement of the linkages.

The handles 2401 are connect by a pivot 2403 for providing force andleverage to the operator of the inserter 2001 as shown in FIGS. 45-48.The handles 2401 are threadably connected, i.e. screwed, by the pivot2403 which provides the pivot axis for the arcuate movement of thehandles.

The ratchet bar 2501 is composed of a rack 2505 connected with a ratchetpin 2507 for providing a safety mechanism to prevent unintendedmechanical release of the implant 100, 200, 300, 400, 500 from theinserter 2001. The rack is composed of a length of teeth shown in FIG.48 that interface with a catch 2405 in the handles 2401 shown in FIG.46. As the handles 2401 are moved together, the catch 2405 willinterface with the teeth of the rack 2505 to allow motion together, suchas by providing shifting mechanical engagement, in only one direction,such as allowing the handles to only move together. This allows theimplant 100, 200, 300, 400, 500 to deploy and distract the vertebrae ofthe spine without the handles moving away from one another due to theforce exerted by the vertebrae on the inserter 2001. As describedpreviously, the ratchet bar can be disengaged to allow the handles 2401to move away from one another. Alternatively, the ratchet pin 2507 canbe coupled to a torsional spring to bias the rack 2505 to the closedposition to prevent any possibility of unintended mechanical release ofthe implant 100, 200, 300, 400, 500.

The screw driver 2601 is composed of a guide spring 2603, a drive head2605, and connector 2607 for providing torque to rotate and secure thefastener of the spinal implant 100, 200, 300, 400, 500. The guide spring2603 is composed of a series of counter poised cantilevered springs tocreate an egg shaped elliptical form that provides a circular linecontact to the through bore 2205 to provide precise rotation of thescrew driver 2601. The drive head 2605 shown is a torx type screw headshown in FIG. 51 but any type of screw head could be used alternatively,i.e. crosshead, slotted, etc. The connector 2607 allows for quickconnection to any of a wide variety of handles for surgical instruments,such as T-bar handles or off-set ratcheted handles.

The counter-torque device 2651 is composed of a counter-torque deviceshaft 2653, a counter-torque device handle 2655, and counter-torquedevice pins 2657 for providing counter-torque to offset the torquecreated by the screw driver 2601 and prevent rotation or dislocation ofthe spinal implant 100, 200, 300, 400, 500. As shown in FIG. 52, thecounter-torque device shaft 2653 fits within the counter-torque devicehandle 2655 with a male and female hexagonal slip fit connection asshown in FIG. 44. The counter-torque device pins 2657 engage grooveswithin the receiving portion of the spinal implant 100, 200, 300, 400,500 to resist torque and rotation.

The nut driver 2701 is composed of an access port 2703, a cantileverspring 2705 as described previously. The nut driver 2701 is alsocomposed of a nut driver shaft 2701 for providing a structuralconnection between the fastener and the operator as shown in FIG. 49.The nut driver connector 2709 again provides a quick connect for variouscommercially available handles as previously described.

The counter-torque handler 2751 is composed of a counter-torque handlershaft 2753, a counter-torque device handle 2755, and counter-torquehandler pins 2757 for providing counter-torque to offset the torquecreated by the nut driver 2701 and prevent rotation or dislocation ofthe spinal implant 100, 200, 300, 400, 500. As shown in FIG. 50, thecounter-torque handler shaft 2753 fits within the counter-torque handlerhandle 2755 with a male and female hexagonal slip fit connection asshown in FIG. 50. The counter-torque handler pins 2657 engage on bothsides of the connector 10001 to resist torque and rotation of both theconnector 10001 and the spinal implant 100, 200, 300, 400, 500.

Insertion of the spinal implant assembly includes multiple steps. First,after sterilizing the surgical field and anesthetizing the patient, asurgical incision is made in the patient from the posterior, or the backof the patient. A posterior approach is used because it provides greateraccess for the surgeon to the boney structures of the spine. The accessto the spine permits surgical implantation of the spinal implant.

Once the incision is made the surrounding tissue is distracted or movedout of the way using standard instruments and methodology. Distractionof tissue at the implantation site provides a direct line of sight forthe surgeon to visually see the implantation of the spinal implant onthe lamina of the spine without causing undue tissue damage.

The spinal implant is then attached to the implant insertion apparatus2001. In the preferred embodiment, the spinal implant 100, 200, 300,400, 500 with the elongate rod member is attached to the insertionapparatus 2001. The spinal implant 100, 200, 300, 400, 500 is attachedby mechanically engaging the elongate rod member to the first grippingportion 2101. The implant 100, 200, 300, 400, 500 engages the firstgripping portion 2101 by inserting the distal end or tip of the elongaterod member into the groove 2103 shown in FIG. 46 at a 45 degree angle.The implant is then rotated about the first gripping portion 2101 untilthe flanges 2105 shown in FIG. 48 engage or fit into the grooves of theelongate rod member of the implant 100, 200, 300, 400, 500.

The implant 100, 200, 300, 400, 500 rod member is rotated until it isparallel to the first gripping portions 2001 and second gripping portion2201. The flange of the spinal implant 100, 200, 300, 400, 500 receivingportion then can be shifted into the fingers 2203 of the second grippingportion 2201 shown in FIG. 45 to surround around the flange of theimplant 100, 200, 300, 400, 500.

The attached implant 100, 200, 300, 400, 500 has a screw driver 2601inserted into the through bore 2205 of the second gripping portion 2201.The screw driver 2601 is placed in contact and mechanically engaged tothe implant fastener. The driver 2601 is then rotated counter clockwiseto loosen the fastener of the spinal implant 100, 200, 300, 400, 500.

The fastener is loosened enough to allow ease of shifting of thereceiving portion on the elongate rod yet maintain connection of thefaster to the implant 100, 200, 300, 400, 500. The fastener is loosenedto allow shifting because of the need to avoid friction by the rod onthe receiving portion when the implant is forcefully driven intoposition on the lamina and to allow the implant to be adjustable.

The upper engagement portion of the spinal implant 100, 200, 300, 400,500 is inserted to engage the inferior portion of a laminar region of avertebral body as shown in FIG. 7A. The installation site of the implantmay be prepared by removing some of the bone of the vertebrae to conformto the surface of the spinal implant thus reducing the risk that theimplant will shift out of position.

The handles 2401 of the inserter 2001 are moved toward and away toadjust the position of the spinal implant so that the lower engagementportion of the spinal implant will engage the superior portion of alaminar region of a second vertebral body. The movement of the handles2401 together maintains the parallel position of the first and secondgripping portion through the mechanical action of the parallel-actionassembly 2301 otherwise known as a scissor lift. The parallel-actionassembly 2301 can be kinematically described as a set of four barlinkages that convert arcuate translation to linear translation. Thehandles 2401 provide mechanical advantage to the surgeon's hands so thatthe vertebral bodies can be distracted sufficiently by the deployment ofthe spinal implant 100, 200, 300, 400, 500 to relieve the pressure bythe facets on the spinal cord or spinal nerves.

The spinal implant 100, 200, 300, 400, 500 is fully deployed when theelongate rod member has reached the end of its travel. Once the spinalimplant 100, 200, 300, 400, 500 has been adjusted to the properpositioned on the spine the lower engagement portion of the implant 100,200, 300, 400, 500 engages the superior portion of a laminar region ofthe second vertebral body.

Once the spinal implant 100, 200, 300, 400, 500 is in proper positionthen the implant fastener must be locked into its final position. Tolock the fastener, the screw driver 2601 has a counter-torque device2651 slipped over the screw driver 2601. The counter-torque device 2651is held in position to prevent the spinal implant 100, 200, 300, 400,500 from moving out of position, i.e. dislocation, due to the torque ofthe screw driver 2601. The torque would otherwise be transmitted to theimplant and spine causing undesired translation as a final lock downtorque is applied by the screw driver 2601 on the fastener of theimplant 100, 200, 300, 400, 500. The final lock down of the fastenersecures the spinal implant 100, 200, 300, 400, 500 to a fixed condition.

A set of spinal implants 100, 200, 300, 400, 500 will typically be usedto structurally support the spine of the patient. The insertion of asecond spinal implant to provide structural support on both sides of thespinous processes of the spine is shown in FIG. 7A. The implants 100,200, 300, 400, 500 are designated left and right to fit the contour ofthe lamina on the left and right sides of the spinous process. Thepairing of spinal implant 100, 200, 300, 400, 500 allows for greaterstability, because the compression loading of the spine is shared byboth implants providing better balance while supporting the spine andpreventing excessive loading on one side of the spine.

A connector 100001, or transverse member 116, can then be added to theset of spinal implants 100, 200, 300, 400, 500 to provide additionalstability. The use of a connector 10001 increases the resistance of thespinal implants to displacement. Specifically, the connector 10001prevents movement of the implants 100, 200, 300, 400, 500 out ofposition should the patient bend or twist because the connector 10001will maintain alignment of the implants with that of the spine.Alternatively however, a standard pedicle screw and distraction rodconnector may also be used to provide a mechanical connection betweenthe spinal implants.

The attachment of the connector begins with attaching a fastener, i.e. ahexagonal nut, to a nut driver 2701 as shown in FIG. 40. The fastener isheld in place by the nut driver 2701 by a female receptacle in the nutdriver 2701 and by deflection of a cantilever spring 2705 shown in FIG.49. The cantilever spring 2705 deflects to allow the fastener to belocked into the nut driver 2701 with a snap fit connection. Should thefastener, such as a hexagonal nut, need to be removed an access port2703 is provided to allow access to the fastener, to remove the fasteneras shown in FIG. 40. Alternatively, other types of mechanical fastenerscan be used such as screws, snap fit connectors, and pins.

The nut driver 2701 and attached fastener, is then placed in contactwith a fastener projection, such as a bolt, on the spinal implant 100,200, 300, 400, 500. A counter-torque handler 2751 is then placed overthe nut driver 2701 to prevent dislocation of the spinal implant duringattachment of the fastener, as shown in FIG. 41.

The nut driver 2701 is rotated and the counter-torque handler 2751 isheld in place to prevent inadvertent dislocation of the spinal implant100, 200, 300, 400, 500 similar to the process done for the screw driver2601. The nut driver 2701 is rotated to secure the connector to thespinal implant 100, 200, 300, 400, 500 to fix the connector 10001 inplace. The process of attaching the fastener is repeated for both spinalimplants 100, 200, 300, 400, 500.

Finally, the inserter apparatus 2001 is removed from the patient anddetached from the implant 100, 200, 300, 400, 500 as shown in FIG. 43.The inserter apparatus 2001 is detached from the implant by firstrotating the ratchet bar 2501 in direction J as shown in FIG. 43. Careshould be taken to grasp the ratchet bar 2501 from the proximal end 2503to prevent inadvertent tearing of surgical gloves due to the sharp edgesof the teeth on rack 2505 of the ratchet bar 2501 mechanism. A smoothand concave grasping point is provided on the proximal end 2503 toprevent the inadvertent tearing of gloves. The inserter apparatus 2001handles 2401 can then be moved away from one another which will causethe second gripping portion 2201 to disengage from the implant. Theinserter apparatus 2001 can then be tilted at a 45 degree angle from theimplant 100, 200, 300, 400, 500 to then disengage the elongate rodmember from the first gripping portion 2101. The inserter apparatus 2001will then be removed from the incision and the patient closed.

Those skilled in the art will recognize that a wide variety ofmodifications, alterations, and combinations can be made with respect tothe above described embodiments without departing from the spirit andscope of the invention, and that such modifications, alterations, andcombinations, are to be viewed as being within the scope of theinvention.

1. A spinal implant assembly for engaging adjacent vertebrae with thespinal implant assembly comprising: a generally U-shaped body having abase portion with opposite ends, spaced side arm portions each having adistal, free end with the spaced side arm portions extending from therespective ends of the base portion; a distal opening at the distal freeends of the spaced side arm portions such that the generally U-shapedbody is open at the distal ends; a stop portion of the base portionextending between the side arm portions; a pair of vertebral engagingarms configured and sized to be received between the side arm portionsfor extending through the distal opening; an arcuate seat of each of thevertebral engaging arms for engaging one of the adjacent vertebrae; anda pivot mechanism for pivotably connecting the vertebral engaging armsand the body portion, the vertebral engaging arms engaged with the stopportion in an operable configuration thereof with the arcuate seatsfacing in generally opposite directions away from each other, and thevertebral engaging arms pivoted away from the stop portion toward eachother with the vertebral engaging arms extending through the distalopening adjacent each other in an inoperable configuration thereof. 2.The spinal implant assembly of claim 1 wherein the vertebral engagingarms include engagement ends having the arcuate seats and intermediateportions, the intermediate portions configured to have a width less thana width of the engagement ends to minimize space between the vertebralengagement arms in the inoperable configuration.
 3. The spinal implantassembly of claim 1 wherein one of the vertebral engaging arms includesa narrow proximal end and the other vertebral engaging arm includes aslotted proximal end configured to receive the narrow proximal endtherein, the proximal ends configured to be received between the sidearm portions.
 4. The spinal implant assembly of claim 1 wherein the bodyportion includes a throughbore and locking mechanism for engaging thevertebral engaging arms and blocking movement thereof while in theoperable configuration.
 5. The spinal implant assembly of claim 4wherein the throughbore is threaded and the locking mechanism is athreaded set screw.
 6. A spinal implant assembly for engaging adjacentvertebrae with the spinal implant assembly comprising: a body having anopening; a first vertebral engaging arm including a first engagement endand a slotted proximal end defined by a pair of spaced arms, the pair ofspaced arms configured to be received in the body opening; a secondvertebral engaging arm having a second engagement end and a narrowproximal end, the narrow proximal end configured to be received betweenthe pair of spaced arms when positioned in the body opening; a pivotmechanism for pivotably connecting the first and second vertebralengaging arms and the body portion with the first and second vertebralengaging arms received in the body opening, the first and secondvertebral engaging arms being pivotable between inoperable and operableconfigurations; and a step on one of the vertebral engaging armsconfigured and arranged to be spaced from the other vertebral engagingarm with the arms in the operable configuration and to contact the othervertebral engaging arm when the arms are pivoted to the inoperableconfiguration in which the first and second engagement ends are adjacentone another.
 7. The spinal implant assembly of claim 6 wherein thesecond engagement end of the second vertebral engaging arm has a distalend width and the narrow proximal end has a narrow width, the narrowwidth being smaller than the distal end width.
 8. The spinal implantassembly of claim 7 wherein the step is positioned on the secondvertebral engaging arm delineating a boundary between the distal endwidth and the narrow width, the step configured to contact a portion ofthe first engagement end when the first and second vertebral engagingarms are in the inoperable configuration.
 9. The spinal implant assemblyof claim 6 further comprising an insertion throughbore on at least oneof the first and second vertebral engaging arms.
 10. The spinal implantassembly of claim 6 further comprising a locking mechanism on the bodyconfigured to prevent movement of at least one of the first and secondvertebral engaging arms.